Studies are proposed to execute the total synthesis of several cyclopentanoid natural products including the antibiotic crinipellin A; the cardiotoxin subergorgic acid; laurenene, the only known naturally occurring fenestrane; retigeranic acid, a novel sesterterpene; and gingkolide A, an unusual molecule which contains three lactones and a t-butyl group. These syntheses will be carried out utilizing intramolecular photocycloadditions of 1,6 dienes to control specific stereochemical elements. An example of asymmetric induction in the intramolecular photocycloaddition will be investigated. An elevated temperature photocycloaddition to introduce highly sterically congested systems will be studied. A novel atom transfer fragmentation to cleave cyclobutyl methyl halides will also be investigated.